The battle against tuberculosis (TB), caused by the bacterium Mycobacterium tuberculosis (Mtb), has raged for millennia. Throughout history, TB has claimed the lives of over one billion people and currently infects one third of the world's population. With 3.1 million deaths a year, TB, as a single causative agent, is the leading killer among infectious diseases. The spread of TB was significantly affected with the advent of several chemotherapy agents during the mid-1900s. However, since the 1980s, TB has been on the rise. Presently, 8 million new cases are added annually.
The increase in cases of TB/HIV co-infection and the spread of multiple-drug resistant TB (MDR-TB, strains that are resistant to first line drugs isoniazid and rifampin) and extensively drug resistant TB (XDR-TB, strains that are resistant to isoniazid and rifampin, as well as any fluoroquinolone and at least one of three injectable second-line drugs, such as amikacin, kanamycin, or capreomycin) are making matters worse. More than ever, there is an urgent need to develop new anti-TB drugs to combat the spread of TB, particularly in its hard-to-kill multidrug-resistant and latent forms.